Synthetic esters

ABSTRACT

A hydraulic fluid consists of, or comprises a synthetic orthoester, or a mixture of synthetic orthoesters, having the general formula represented by A or B:   wherein R1, R2 and R3 are specified groups. Also described are methods of making compositions which comprise a major proportion of the synthetic orthoesters and novel synthetic orthoesters of the formula:   WHEREIN R4 and x are specified groups.

United States Patent [191 Elliott et al.

[ Sept. 2, 1975 SYNTHETIC ESTERS [75] Inventors: John Scotchford Elliott; Monty Frederick Crook; Gerald John Joseph Jayne, all of London,

England [73] Assignee: Castrol Limited, London, England [22] Filed: May 8, 1972 211 App]. No.: 251,524

Related US. Application Data [62] Division of Ser No. 98,963, Dec. 16,

abandoned.

[52] US. Cl. 252/79; 252/73; 260/615 A [51] Int. Cl? C09K 3/00; ClOM 3/20 [58] Field of Search 252/73, 615 A, 79

[56] References Cited UNITED STATES PATENTS l/l959 Dermer et al 260/615 A 11/1967 Kuryla 260/615 A X Primary ExaminerRalph S. Kendall Assistant Examinerl-larris A. Pitlick Attorney, Agent, or Firm-Bacon & Thomas wherein R, R and R are specified groups. Also described are methods of making compositions which comprise a major proportion of the synthetic orthoesters and novel synthetic orthoesters of the formula:

wherein R and x are specified groups.

13 Claims, No Drawings SYNTHETIC ESTERS This is a division of application Ser. No. 98,963 filed Dec. 16, 1970 and now abandoned.

The present invention relates to synthetic orthoesters suitable for use in hydraulic fluids, some of which orthoesters are novel compounds.

According to the present invention there is provided a hydraulic fluid consisting of, or comprising, a synthetic orthoester having the general formula represented by A or B:

OR H2 0H2 I I I R C-0R R -c-R -c-R I I 0R2 OR2 OR wherein R is a hydrogen atom, an alkyl radical containing from 1 to carbon atoms, or the same as 0R each R is the same or different and each is an alkyl radical containing from 1 to 4 carbon atoms, an oxyalkylene glycol mono ether radical, or a polyoxyalkylene glycol mono ether radical containing from 2 to 20 alkylene oxy units, provided that at least one R is an oxyalkylene glycol mono ether radical or a polyoxyalkylene glycol mono ether radical;

and R is an alkylene radical containing from 1 to 12 carbon atoms, provided that R is then the same as OR or R is the group (-OR O+ wherein each R is the same or different and each is an alkylene radical containing from 2 to 8 carbon atoms and .r is an integer from 1 to 6, or a mixture of two or more such synthetic orthoesters.

In another aspect of the present invention the hydraulic fluid comprises from 1 to 99 percent by weight, based on the weight of the hydraulic fluid, of the foregoing orthoesters.

In a further aspect of the present invention there is provided a hydraulic system containing the hydraulic fluids of the present invention. In yet another aspect of the present invention there is provided a method of transmitting power in a hydraulic system, which method comprises introducing into the system a hydraulic fluid in accordance with the present invention and transmitting power by applying pressure thereto.

The orthoesters employed in the hydraulic fluids are particularly useful when employed in minor amounts, e.g. l to 50 percent by weight, as water scavengers. In a preferred form of the invention the orthoesters are used in amounts of l to 30 percent, more preferably 5 to 20 percent by weight.

In those orthoesters which are particularly useful as hydraulic fluids, or components thereof, preferably R is a hydrogen atom, an alkyl radical containing 1 or 2 carbon atoms, or is the same as 0R each R is the same or different and each is an alkyl radical containing 1 or 2 carbon atoms, or R is the radical --(R O),,R wherein each R is the same or different and each is an alkylene radical containing from 2 to 4 carbon atoms, each R is the same or different and each is an alkyl radical containing from 1 to 4 carbon atoms, more preferably 1 or 2 carbon atoms, and n is an integer from 1 to 4, provided that at least one R more preferably 2 or 3 (in the case of formula A) or at least 3 (in the case of formula B) is the radical (R O),,R and R is an alkylene radical containing from 1 to 6 carbon atoms, provided that R is then the same as OR, or R is the group O+RO) wherein each R is the same or different and each is an alkylene radical containing from 26 carbon atoms and x is an integer from 1 to 4 Particularly preferred compounds suitable for use in hydraulic fluids are the orthoformates, orthoacetates, and orthopropionates of the monoethyl or monomethyl ethers of ethylene glycol, diethylene glycol or triethylene glycol or of propylene glycol, dipropylene glycol or tripropylene glycol or the orthoformate, orthoacetate and orthopropionate esters derived from mixtures of the above-mentioned glycol ethers. Alternatively, the corresponding orthocarbonates may be employed, if desired.

The hydraulic fluids of the present invention may contain, for example, in major amounts, polyoxyalkylene glycol ether esters of dicarboxylic acids such as those described in UK. Pat. No. 1,083,324 or alkyl esters of polyoxyalkylene glycols or glycol ethers having the formula:

wherein R is an alkyl group containing from 1 to 4, preferably 1 or 2, carbon atoms or is the group CO R', v is an integer of from 1 to 4, preferably 2 or 3, each R" is the same or different and is an alkylene group containing from 1 to 4, preferably 2 or 3, carbon atoms and R'" is an alkyl group containing from 1 to 4, preferably 2 or 3 carbon atoms.

Alternatively the hydraulic fluids of the present invention may'contain major amounts of polyoxyalkylene glycols or ethers thereof. Examples of such glycols and ethers are ethylene glycol, diethylene glycol, triethylene glycol, the corresponding propylene glycols, the monomethyl and monoethyl ethers of the foregoing glycols, mixed ethylene/propylene glycols and ethers thereof and commercially available mixtures of glycols and/or glycol monoethers such as those marketed under the trade names PEG 200 and Ucons. The glycols and glycol ethers may also be blended with the polyoxyalkylene glycol ether esters of dicarboxylic acids hereinbefore described. However, in order to preserve the desirable low hygroscopicity of the esters it is preferred that not more than 10 percent by weight of the polyoxyalkylene glycols and ethers are blended therewith.

Other components which may be included in the hydraulic fluids of the present invention include the cyclic alkylene carbonates, and carbonates derived from the monomethyl and monoethyl esters of ethylene glycol, diethylene glycol and triethylene glycol.

The hydraulic fluid compositions of the present invention preferably have a viscosity of less than 5,000 cSt, more preferably less than 2,000 cSt, at 40C, and a boiling point of at least 260C. In addition the hydraulic fluids are preferably blended so as to satisfy the rubber swell requirements of the S.A.E. J 1703b Specification.

It will be understood that the hydraulic fluid compositions of the present invention may contain small amounts of the usual and well-known hydraulic fluid additives, particularly but not exclusively lubricity agents and corrosion inhibitors.

As hereinbefore described, certain of the orthoesters used in the hydraulic fluids of the present invention are novel compounds. Accordingly the present invention also provides as new compounds orthoesters or mixtures of orthoesters having the general formula:

on on l R1 a c': o (R o) c R1 x I B2 0B2 wherein R, R, R and x are as hereinbefore defined.

The compounds which form the essential components of the hydraulic fluids of the present invention are orthoesters and several methods of preparing orthoesters are known. For example, reaction of hydrogen cyanide and gaseous hydrogen chloride with absolute alcohol produces an intermediate imido ether hydrochloride which reacts with further alcohol in the presence of a base to produce an orthoester and ammonium chloride. The reaction is normally carried out in a solvent, such as chlorobenzene, diethyl ether, chloroform, 0- dichlorobenzene or petroleum ether, from which the ammonium chloride precipitates. In a variation of this reaction (Pinner synthesis) the alcohol and gaseous hydrogen chloride are reacted with a nitrile or a dinitrile compound, for example adipo-l,6-dinitrile may be reacted, e.g. by the method of U.l(. Pat. No. 1,128,963, to yield an orthoadipate. In a second preparative method a halo compound, such as vinylidene chloride, is reacted with a sodium alcoholate, such as that derived from diethylene glycol monomethyl ether, in an excess of the glycol ether, in a variation of the well known Williamson ether synthesis, for example by the method of U.S. Pat. No. 3,419,580.

Accordingly the present invention further provides a method of preparing a composition comprising a major amount of a synthetic orthoester, or a mixture of synthetic orthoesters, having the general formula represented by A or B:

2 9 2 9 2 k 0R2 R c R c R m on OR2 wherein R is an alkyl radical containing from 1 to carbon atoms and R and R are as defined in claim I, said composition being suitable for use in a hydraulic fluid, which method comprises reacting a sodium alcoholate of a monoether of an oxyalkylene or polyoxyalkylene glycol, the alcoholate having the general formula R ONa, with a halo compound having the general formula R C CX wherein R is a hydrogen atom or an alkyl group containing from I to 4 carbon atoms and each X is the same or different and each is a halogen atom.

Yet another possible method of preparation involves reaction of trialkyl orthoesters with alkylene oxides to yield tris glycol ether orthoesters or mixed glycol etherlalkyl orthoesters (in the manner of U.S. Pat. No. 2,867,667).

A convenient method of preparing the orthoesters employed in the hydraulic fluids of the present invention is by transesterification with a lower alkyl, e.g. methyl or ethyl, orthoester in the presence of a catalyst. Examples of useful lower alkyl orthoesters are trimethyl and triethyl orthoformate, orthoacetate and orthopropionate and Friedel Crafts catalysts, particularly aluminium chloride, are exemplary of utilisable catalysts. Other catalysts which may be used are ion exchange resins, hydrogen chloride gas, lower (e.g. C aliphatic carboxylic acids and activated earth catalysts.

Accordingly the present invention further provides a method of preparing a composition comprising a major amount of a synthetic orthoester, or a mixture of synthetic orthoesters, having the general formula:

9 Alkyl R1 g 0 Alkyl o Alkyl with a compound of the formula R OH so as to produce a product containing as a major component a compound of the formula R1 c OR In the case of the novel orthoesters of the present invention, the transesterification is conveniently carried out in two stages. Firstly a trialkyl orthoester is transesterified with a monoether of an oxyalkylene or polyoxyalkylene glycol in the presence of a catalyst and in a molar ratio such that two of the alkyl groups in the initial orthoester are replaced by glycol monoether residues. The product from the first stage is then further transesterified with an alkylene, oxyalkylene or polyoxyalkylene glycol.

Accordingly the present invention also provides a method of preparing a composition comprising a major amount of a synthetic orthoester, or a mixture of synthetic orthoesters, having the general formula:

I V I n c o (n o) c a v x I 2 0R2 on wherein R, R R" and x are as hereinbefore defined, said composition being suitable for use in a hydraulic fluid, which method comprisestransesterifying a trialkyl orthoester of the formula:

0 Alltyl a c o-- Alkyl O Alkyl with a compound of the formula R OH so as to produce a product containing as a major component a compound of the formula:

I R -CO-Alltyl I CR2 and thereafter transesterifying the product with a diol of the formula H O (RO), H. Preferably both transesterifications are carried out in the presence of an aluminium chloride catalystandwith substantially stoichiometric quantities of reactants. In the case of the second transesterification it is preferred to carry out the reaction in the presence of further quantities of the compound R OH.

There now follows by way of example a description of preparations of the orthoesters and hydraulic fluids containing the orthoesters in accordance with the present invention.

EXAMPLE I 148 g. 1.0 mole) of triethyl orthoformate, 592 g. (3 mole) triethylene glycol monoethyl ether which had been previously dried by molecular sieves, and l g. of aluminium trichloride were stirred under reflux in a nitrogen atmosphere. ll4 g. (Theory 138.6 g.) ethanol was distilled out during the reaction through a 9 inch column packed with Fenske helices. The product was dissolved in toluene, washed with ml. of water, filtered and dried over magnesium sulphate and the solvent distilled off under vacuum. From infra-red analysis it was inferred that the product was tris (ethyl triglycol) orthoformate. This had a viscosity at -40C of 1,521 cSt.

EXAMPLES 2 to 16 Further esters were prepared in similar manner to Example I, the relevant details of the preparations being set out in Table l.

EXAMPLE 17 296 g. (2.0 mole) of triethyl orthoformate and 480 g. (4.0 mole) diethylene glycol monomethyl ether were reacted in the presence of l g. of aluminium trichloride for 2% hours at a temperature at 148C, during which period 142.5 g. ethanol (theory 184 g.) were distilled off. A further I g. of aluminium trichloride was then added together with 48 g. diethylene glycol monomethyl ether and 106 g. (1.0 mole) diethylene glycol.

The resultant mixture was further reacted for 5 hours at a temperature of l50l85C, during which period g. ethanol (theory 92 g.) were distilled off. Further heating to 200C gave no more distillate.

The distillation residue was cooled and then stirred for 2 hours with 30 ml. of water, filtered, dried over magnesium sulphate and low boiling components distilled off at l90C under vacuum.

The residue was a viscous liquid (yield 266 g. 44 percent), infra-red analysis of which was consistent with its being predominantly diethylene glycol bis di(diethylene glycol monomethyl ether) orthoformate together with small amounts of unreacted glycol and/or glyol ether.

EXAMPLE 1 8 Hexamethylene glycol bis di( diethylene glycol monomethyl ether) orthoformate was prepared by a similar process to Example 17. The first transesterification was the same as in Example 17 except in that the starting materials were reacted for 8 hours at l25-l30C to give 193 g. of ethanol distillate. To the product (distillation residue) of the first transesterification were added 1 g. aluminium trichloride, 48 g. diethylene glycol monomethyl ether and 1 18 g. l .0 mole) hexamethylene glycol. Evolution of ethanol (63.2 g.) occurred slowly over a period of 3 hours. ml. dimethyl formamide solvent and l g. aluminium trichloride were then added, but no further ethanol was evolved. On addition of 74 g. (0.5 mole) triethyl orthoformate and a further 1 g. aluminium trichloride and refluxing for 2 hours a further 29.7 g. ethanol were evolved.

The product was dissolved in toluene, stirred with water and filtered, low boiling components of the filtrate then being distilled off at 200C under vacuum.

The final product (yield 514 g. 83 percent) was shown by infra-red analysis to contain small amounts of free glycol and/or glycol ether.

EXAMPLE 19 A mixture of the sodium alcoholate of diethylene glycol monomethyl ether in the glycol ether was prepared by reacting 3.3 moles (396 gm.) of diethylene glycol monomethyl ether with 2.0 moles (46 gm.) of metallic sodium under a nitrogen atmosphere and at a temperature of about 100C. To this mixture was slowly added over three-fourths hour, with stirring, 1.0 mole (97 gm.) of vinylidene chloride under a nitrogen atmosphere during the course of which the temperature of the reaction mixture increased from l00l40C, and a precipitate of sodium chloride was formed. The reaction mixture was heated to C for one-fourth hour and when cool was filtered to remove the salt. This was washed with diethyl ether and dried in a vacuum oven (yield 109.5 gm. theory 2 moles, ll7 gm. of NaCl).

The ether washings and filtrate were combined, and the mixture was concentrated by removal of the ether, followed by stripping under reduced pressure to a base temperature of 200C and stillhead temperature 80C at 6mm. of mercury. The residue was an amber liquid (258 gm. 67 percent), lR analysis of which showed it to be predominantly tris (methyl diglycol) orthoacetate free of unreacted glycol ether. Analysis also showed very little normal ester (carbonyl peak C=O at l735 cm) or C=CH to be present.

TABLE 1 yield Example Wt. Wt. Al Cl; Wt.

No. Glycol Ether (g) Moles Starting Ester (g) Moles Wt. (g) Product (g) 71 2 tricthylenc glycol 267 1.65 tricthyl 88 0.5 0.5 tris( methyl 206 77.6

monomethyl cther orthopropionatc triglycol)orthopropionatc 3 diethylene glycol 1980 16.5 triethyl orthoformate 740 5.0 tris(mcthyl 1509 81.5

monomethyl ether diglycol)orthoformate 4 triethylene glycol 2070 12.62 triethyl orthoformate 565 3.82 4 tris(methyl 1264 65.5

monomethyl ether triglycol)orthofor mate 5 triethylene glycol 267 1.65 triethyl orthoacetate 81 0.5 0.5 tris( methyl 142 68 monomethyl ether triglycol)orthoacetate 6 triethylene glycol 534 3.3 triethyl 176 l 2.0 tris( methyl 260 49 monomethyl ether orthopropionate trig1ycol)orthopropionate 7 dipropylene glycol 444 3.0" triethyl orthoformate 148 1 l tris(dipropylene 266 58.5

monomethyl ether glycol monomethyl ether) orthoformate 8 ethylene glycol 456 6.0" triethyl orthoformate 296 2.0 2" tris(methyl 380 83.5

monomethyl ether glycol)orthoformate 9 diethylene glycol 221 1.845 triethyl orthovalerate 99.6 0.615 0.2 tris( methyl 196 74 monomethyl ether diglycol)orthovalerate l0 tetraethylene glycol 1.5' triethyl orthoformate 74 0.5 l" tris( methyl 183 57.5

monomethyl ether tetraglycol) orthoformate l l diethylene glycol 426 3.0" triethyl orthoformate 148 I l tris(butyl diglycol) 269 54 monobutyl ether orthoformate l2 diethylene glycol 402 3.0 triethyl orthoformate 148 1.0 I tris(ethyl diglycol) 255 62 monoethyl ether orthoformate l3 diethylene glycol 1080 9.0 triethyl orthoacetate 486 3.0 1.5" tris(methyl diglycol) 991 86 monomethyl ether onhoacetate l4 diethylene glycol 961 8.01" triethyl 469 2.67 1.3" tris( methyl diglycol) 728 68.5

monomethyl ether orthopropionate orthopropionate triethylene glycol 534 3.0" triethyl orthoformate 148 1.0 0.7 tris(ethyl triglycol) 350 64 monoethyl ether orthoformate l6 l-butoxy 1056 6.0 triethyl orthofoririate 296 2.0 2.0 tris( l-butoxyethoxy- 91 1 84.7

ethoxy-2-propanol Z-propyl )orthoformate FOOTNOTES TO TABLE 1 "Further glycol other (0.3 mole) added after 5 hours. "Further glycol ether (0.6 mole) added after 6%: hours. "Further catalyst (l g.) added after 5 houis. "Further catalyst l g.) added after 6% hours and 9 hours. "Further Catalyst (1 g.) added after 3 hours and 6 hours. 'Further catalyst (0.2 g.) added afier 3% hours. "Starting ether contained 7171 tctraethylenc glycol monomethyl ether. "Further 107: glycol ether added after rapid evolution of ethanol ceased (4-6 hours). Further quantity of catalyst added after rapid evolution of ethanol ceased. "Fulcat l4 (activated earth) catalyst used in place of Al Cl and further quantity of catalyst added after rapid evolution of ethanol ceased. Further glycol ether (0.6 mole) and catalyst l g.) added after 6 hours.

The suitability of the orthoesters for inclusion in hylus the f ll ing com ination of additives:

Di-nutylamine 005% draulic fluids was evaluated by determining the follow Benzmriazolc 0.05% mg properties: Triphenyl phosphitc 015% a. The boiling point of the orthoesters. "P l' W primaryzsamratedi a straight chain aliphatic monoamine (95% b. The viscosity of the orthoesters at -40 F. primary 5% Secondary and miary amines; c. The effect of the inclusion of the orthoesters on the g y: chains being 97% 12; 2% H and I l iu bollmg pomt of hydrauhc fiuld both m the pres- Agerite Resin D (commercially available poly- 0.05%

(i) Base fluid consisting of:

Di(monomethyl ether of dicthylene glycol )nylonate 39% Triethylene glycol dipropionate 4571 Monomethyl ether of triethylene glycol 5% Monocthyl ether of triethylene glycol 57( Reoplex 641 (a commercially available lubricity 371 additive) Amine A 371 merised trimethyl dihydro quinoline resin) Amine A was a condensation product of propylene oxide (5.5 mole) with ammonia (1 mole) and Reoplex 641 was a complex ester of molecular weight about 7 12 derived from neopentyl glycol and a mixture of sebacic, azelaic and adipic acids in respective proportions, determined by analysis, of 53, 5 and 38 percent. The nylonate ester was an ester of a mixture of dicarboxylic acids as described in U.K. Pat. No. 1,083,324.

(ii) Base fluid 10 percent orthoester.

(iii) Base fluid 10 percent orthoester 1 percent water.

The results of the evaluation of the orthoesters are shown in Table 2.

TABLE 2 Boiling points (F) Boiling Rubber swell Rubber swell Viscosity 7 Base fluid* Base fluid* point (natural rubber) (synthetic rubber) Orthoestcr at 40F Orthoestcr 10% 10% drop in 7: volume in volume cSt) Orthoester Orthoester (F) increase increase 1% water 3 days 3 days Product of Ex.2 2048 476 5.6 24.6 Product of Ex.3 452 540 2.6 17.7 Product of Ex.4 3027 552 0.32 11.7 Product of Ex.5 3449 495 0.6 10.6 Product of Ex.6 2756 478 556 453 103 2.6 16.0 Product Of Ex.7 589 496 514 428 86 43.4 59.4 Product of Ex.8 89 484 439 383 56 17.2 500 Product of Ex) 205 453 550 432 118 65.5 Product of Ex. 10 10.023 594 583 457 126 2.3 2.7 Product of Ex.11 468 540 441 99 43.6 74.3 Product of Ex. 12 561 541 545 433 112 12.1 34.4 Product of Ex. 13 404 469 538 428 l 10 6.4 23.4 Product of Ex.l4 536 437 527 419 108 14.3 40.1 Product of Ex. 15 1943 531 577 466 111 2.2 13.9 Product of Ex.16 1098 513 547 421 126 69.6 56.4 Product of Ex. 17 Too vis- 538 550 439 111 0.5 5.9

cous for determination Product of Ex.l8 3247 527 536 451 85 1 1 12.2 Product of Ex. 19 806 475 543 453 90 23.1

Base fluid has viscosity at 40F of 1.700 est, a boiling point of 576F and a boiling point of 396F (drop 180F) whcn containing W: Water.

- from the atmosphere by hygroscopic components of the fluid.

In further tests blends of the orthoacetate and orthopropionates of the monomethyl ethers of diethylene glycol were tested for compliance with the requirements of the SAE .11703b Specification and compared with a similar blend which did not contain an orthoester. The blends tested consisted of the following components:

Ester base 84% Monoethyl ether of) 10% triethylene glycol) Reoplex 641 3% Amine A 3% plus the same combination of additives as employed in the base fluid hereinbefore described.

Three blends were tested in which the ester base was as follows:

Blend Blend Blend 1 2 3 Di(monomethyl ether of diethylene 48% glycol )nylonate Triethylene glycol dipropionate 39% 24% 26% Tris(methyl diglycol)orthoacetate 10% Tris( methyl diglycol orthopropionate) 107:

The blends containing the orthoesters were found to comply in all respects with the requirements of the SAE J 1703b Specification, as shown by the test results set out in the following Table 3.

TABLE 3 RESULTS TEST REQUIREMENT BLEND 1 BLEND 2 BLEND 3 BOILING POINT 190C min 310 277 275 FLASH POINT 82C min 182 157 166 VISCOSITY (cS): at -40C 1800 max 1694 1721 1779 50C 4.2 min 5.4 6.35 6.14 C 1.5 min 2.18 2.26 2.21 pH VALUE 7.0 11.5 8.6 9.05 8.75 FLUID STABILITY: high temperaallowed ture stability change 30C 005 for 4 -3 every degree b.pt. exceeds 225C. chemical allowed stability change 2C 1 1 Nil max. CORROSION: wcight change g/ m") tinned iron 0.2 max +0.005 +0.0l8 +0.005 steel 0.2 max +0.008 +0.017 0.004 aluminium 0.1 max 40.008 +0.0l3 -0.004 cast iron 0.2 max +0032 +0.030 +0.004 brass 0.4 max 0.029 Nil 0.066 cOppcr 0.4 max ().()13 +0.02l ().O33 pitting Nil Nil Nil Nil gclation of test fluid Nil Nil Nil Nil formation of crystal- Nil Nil Nil Nil line deposit TABLE 3 COntinued RESULTS TEST REQUIREMENT BLEND l BLEND 2 BLEND 3 sedimentation 0. 171

(by volume) 0.03 0.01 0.01

max pH value 7.0 11.5 7.1 7.06 7.2 SBR cup: tackiness Nil Nil Nil Nil blisters Nil Nil Nil Nil carbon black Nil Nil Nil Nil hardness decrease 15 max 5 4 4 base diameter increase 1.4 mm max 0.76 0.61 0.93 FLUIDITY AND APPEARANCE AT LOW TEMPERATURES: 40C hiding power clearly clearly clearly clearly chart discemable discemable discernable discernable Stratification Nil Nil Nil Nil sedimentation Nil Nil Nil Nil bubble inversion secs max 4 3 3 time 50C hiding power clearly clearly clearly clearly chart discernable discemable discernable discernable stratifieation Nil Nil Nil Nil sedimentation Nil Nil Nil Nil bubble inversion secs max 6 4 5 time EVAPORATION weight loss 80% max 16.9 23 25 gritty or abrasive Nil Nil Nil Nil residue pour point of 5C max 20 -20 -20 residue WATER TOLERANCE at C hiding power clearly clearly clearly clearly chart discernahle discemable discernable discernable stratification Nil Nil Nil Nil sedimentation Nil Nil Nil Nil bubble inversion 10 secs max 3 3 3 time at C Stratification Nil Nil Nil Nil sedimentation 0.05% max Nil 0.04 Nil COMPATIBILITY at 40C hiding power clearly clearly clearly clearly chart discernable discemable diseernable discernable Stratification Nil Nil Nil Nil sedimentation Nil Nil Nil Nil at 60C stratification Nil Nil Nil Nil sedimentation 0.05% max Nil Nil Nil RESISTANCE TO OXIDATION weight loss g/ aluminium 0.05 max 0.0l7 0.002 +0.012 cast iron 0.3 max 0.005 +0.020 +0.0I6 pitting roughening Nil Nil Nil Nil EFFECT ON SBR CUP 120 hrs at C hardness increase Nil Nil Nil Nil hardness decrease 10 max 9 9 5 base diameter increase 0.]5 1.4mm 0.91 0.74 0.78 tackiness not excessive Nil Nil Nil blisters Nil Nil Nil Nil carbon black Nil Nil Nil Nil 70 hrs at C hardness increase Nil Nil Nil Nil hardness decrease 15 max 13 6 9 base diameter increase 0.15 l4mm l.l6 l.0l L33 tackiness not excessive Nil Nil Nil. blisters Nil Nil Nil Nil Nil Nil Nil Nil sloughing We claim: i. polyoxyalkylene glycol ether esters of dicarbox- 1. In the operation of a fluid pressure operating deylic acids; vice which uses hydraulic pressure transmission fluid, ii. alkyl esters having the general formula: the improvement comprising using as said hydraulic I u m pressure transmission fluid a composition including as R o the base fluid at least one orthoester of the formula: 0 wherein R is selected from the group consisting of alkyl radicals from 1 to 4 carbon atoms and 2 radicals having the formula -COR', y is an integer of from 1 to 4, each R" is the same or difl c ferent and is an alkylene group containing 1 to 4 I carbon atoms and R' is an alkyl group containing from 1 to 4 carbon atoms; iii. polyoxyalkylene glycols; and wherein R is selected from the group consisting of hy- P y y y glycol eihers; the synthetic drogen atoms and alkyl radicals containing from 1 to 5 i5 thOeStel' OI'thOeSteIS being Present in the carbon atoms; R is selected from radicals having the in an amount of at least about 1 Pe cen y formula +RO ,,+R" wherein R" is an alkylene radical Weight provided that at least one R in the case containing from 2 to 4 carbon atoms, R is an alkyl radof formula A, or at least three R in the case of ical containing from 1 to 4 carbon atoms, and n is an formula B be the radical +RO+1|R as defined integer from I to 20. above.

2. In the operation of a fluid pressure operating de- 3. The improvement defined in claim 2 wherein said vice which uses hydraulic pressure transmission fluid, synthetic orthoester has the general formula reprethe improvement comprising using as said hydraulic sented by A or B in which: pressure transmitting fluid a composition consisting es- R is selected from the group consisting of hydrogen mi ll f; atoms, alkyl radicals containing from 1 to 2 carbon a. at least one synthetic orthoester having the general atoms and radicals having the formula 0R each formula represented by A or B: R is the same or different and each is selected OR 2 OR 2 OR 2 l l I R 'COR R CR 'R OR OR OR wherein: I from the group consisting of alkyl radicals containi. R is selected from the group consisting of hydroing from 1 to 2 carbon atoms and radicals having gen atoms, alkyl radicals containing from 1 to 5 the formula +RO+,, R wherein each R is the carbon atoms and radicals having the formula same or different and each is an alkylene radical 0R containing from 2 to 4 carbon atoms, each R is the ii. each R is the same or different and each is sesame or different and each is an alkyl radical conlected from the group consisting of alkyl radicals taining from 1 to 4 carbon atoms, and n is an intecontaining from 1 to 4 carbon atoms and radicals ger from 1 to 4; and R is selected from the group having the formula (-RO-)-,,R wherein each R a consisting of alkylene radicals containing from 1 to is the same or different and each is an alkylene 6 carbon atoms, and radicals having the formula radical containing from 2 to 4 carbon atoms, -O+RO+, wherein each R is the same or difeach R is the same or different and each is an ferent and each is an alkylene radical containing alkyl radical containing from 1 to 4 carbon atoms i from 2 to 6 carbon atoms and x is an integer from and n is an integer of from 1 to 20; I t l to 4.

iii. R is selected from the group consisting of alkyl- 4. The improvement defined in claim 3 wherein said ehe radicals Containing from i to 12 Carbon synthetic orthoester has the general formula repreatoms and radicals having the formula -O-(-R- sented b A in which each R4 is the Same different 5. The improvement defined in claim 3 wherein said and each is an aikyieiie i'adicai Containing from synthetic orthoester has the general formula repre- 2 to 8 carbon atoms and X is an integer of from sented b B 1 t0 Provided that R] is the Same as 0R2 when 6. The improvement defined in claim 3 wherein said R3 is an aikyiehe radicai containing from i to i2 synthetic orthoester has the general formula reprecarbon atoms; or, sented by A or B and in which each R in the +R- b. a mixture of at least one synthetic orthoester havd-" is the Same or different and each is an aikyi ing aid gener l formula re e nt d b A o B t radical containing from 1 to 2 carbon atoms.

gether with at lea t one h d li fl id b to k 7. The improvement defined in claim 6 wherein said selected from: synthetic orthoester has the general formula represented by A and at least 2 of the R groups have the formula +RO+,,R

8. The improvement defined in claim 2 wherein the hydraulic pressure transmitting fluid consists essentially of the mixture (b) and wherein the synthetic orthoester or orthoesters are present in such mixture in an amount of from 1 to 30 percent by weight.

9. A hydraulic pressure transmitting fluid consisting essentially of a mixture of:

a. at least one synthetic orthoester having the general formula represented by A or B:

2 OR OR 1 l R c R R 2 OR OR wherein:

i. R is selected from the group consisting of hydrogen atoms, alkyl radicals containing from 1 to carbon atoms and radicals having the formula 0R ii. each R is the same or different and each is selected from the group consisting of alkyl radicals containing from 1 to 4 carbon atoms and radicals having the formula +RO+,,R" wherein each R is the same or different and each is an alkylene radical containing from 2 to 4 carbon atoms, each R is the same or different and each is an alkyl radical containing from 1 to 4 carbon atoms and n is an integer of from 1 to and iii. R is selected from the group consisting of alkylene radicals containing from 1 to 12 carbon atoms and radicals having the formula Ot-R- 0+, in which each R is the same or different and each is an alkylene radical containing from 2 to 8 carbon atoms and X is an integer of from 1 to 6; provided that R is the same as OR when R" is an alkylene radical containing from 1 to 12 carbon atoms; and

b. at least one hydraulic fluid base stock selected from:

i. polyoxyalkylene glycol ether esters of dicarboxylic acids;

ii. alkyl esters having the general formula:

RIO 11 1u wherein R is selected from the group consisting of alkyl radicals from 1 to 4 carbon atoms and radicals having the formula COR, y is an integer of from 1 to 4, each R" is the same or different and is an alkylene group containing I R3 CR present in amount of from 1 to 30 percent by weight. 1 l. The hydraulic pressure transmitting fluid of claim 9 wherein a minor amount of a corrosion inhibiting hydraulic fluid additive is present in the mixture.

12. A hydraulic pressure transmitting fluid consisting essentially of at least one synthetic orthoester having the general formula of at least one synthetic orthoester having the general formula represented by A or B:

wherein:

i. R is selected from the group consisting of hydrogen atoms, alkyl radicals containing from 1 to 5 carbon atoms and radicals having the formula 0R ii. Each R is the same or different and each is selected from the group consisting of alkyl radicals containing from 1 to 4 carbon atoms and radicals having the formula (-RO-)-,,R wherein each R is the same or different and each is an alkylene radical containing from 2 to 4 carbon atoms, each R is the same or different and each is an alkyl radical containing from 1 to 4 carbon atoms and n is an integer of from 1 to 20; and

iii. R is selected from the group consisting of alkylene radicals having the formula -(-ORO+ in which each R is the same or different and each is an alkylene radical containing from 2 to 8 carbon atoms and X is an integer of from 1 to 6; provided that R is the same as OR when R is an alkylene radical containing from 1 to 12 carbon atoms; and a minor amount of a corrosion inhibiting hydraulic fluid additive provided that at least one R in the case of formula A, or at least three R in the case of formula B be the radical t-RO+,,R as defined above.

13. The hydraulic pressure transmitting fluid of claim 12 the synthetic orthoester component comprises tris (methyl triglycol) orthopropionate.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 1 3,903,006 DATED September 2, 1975 INV ENTOR(S) John Scotchford Elliott; Monty Frederick Crook;

I Geral John Joseph Jayne It :scertnred that error appears m the ab0ve-rdes1rrfred patent and that sald Letters Patent are hereby corrected as shown below;

Col. 1, beneath Related U.S. Application Data insert Foreign Application Priority Data: December 16, 1969 British Provisional Specification No. 6l30l/69 Signed and Scaled this fourth Day Of November 1975 [SEAL] A ttes t:

RUTH C. MASON C. MARSHALL DANN Alresling Officer (bmmissiuner nfParems and Trademarks 

1. In the operation of a fluid pressure operating device which uses hydraulic pressure transmission fluid, the improvement comprising using as said hydraulic pressure transmission fluid a composition including as the base fluid at least one orthoester of the formula: 2.IN THE OPERATION OF A FLUID PRESSURE OPERATING DEVICE WHICH USES HYDRAULIC PRESSURE TRANSMISSION FLUID, THE IMPROVEMENT COMPRISING USING AS SAID HYDRAULIC PRESSURE TRANSMITTING FLUID A COMPOSITION CONSISTING ESSENTIALLY OF: A. AT LEAST ONE SYNTHETIC ORTHOESTER HAVING THE GENERAL FORMULA REPRESENTED BY A OR B:
 3. The improvement defined in claim 2 wherein said synthetic orthoester has the general formula represented by A or B in which: R1 is selected from the group consisting of hydrogen atoms, alkyl radicals containing from 1 to 2 carbon atoms and radicals having the formula OR2; each R2 is the same or different and each is selected from the group Consisting of alkyl radicals containing from 1 to 2 carbon atoms and radicals having the formula -R6O-n R5 wherein each R6 is the same or different and each is an alkylene radical containing from 2 to 4 carbon atoms, each R5 is the same or different and each is an alkyl radical containing from 1 to 4 carbon atoms, and n is an integer from 1 to 4; and R3 is selected from the group consisting of alkylene radicals containing from 1 to 6 carbon atoms, and radicals having the formula -O-R4O-x wherein each R4 is the same or different and each is an alkylene radical containing from 2 to 6 carbon atoms and x is an integer from 1 to
 4. 4. The improvement defined in claim 3 wherein said synthetic orthoester has the general formula represented by A.
 5. The improvement defined in claim 3 wherein said synthetic orthoester has the general formula represented by B.
 6. The improvement defined in claim 3 wherein said synthetic orthoester has the general formula represented by A or B and in which each R5 in the -R6O-nR5 is the same or different and each is an alkyl radical containing from 1 to 2 carbon atoms.
 7. The improvement defined in claim 6 wherein said synthetic orthoester has the general formula represented by A and at least 2 of the R2 groups have the formula -R6O- nR5.
 8. The improvement defined in claim 2 wherein the hydraulic pressure transmitting fluid consists essentially of the mixture (b) and wherein the synthetic orthoester or orthoesters are present in such mixture in an amount of from 1 to 30 percent by weight.
 9. A hydraulic pressure transmitting fluid consisting essentially of a mixture of: a. at least one synthetic orthoester having the general formula represented by A or B:
 10. The hydraulic pressure transmitting fluid of claim 9 wherein the synthetic orthoester or orthoesters are present in amount of from 1 to 30 percent by weight.
 11. The hydraulic pressure transmitting fluid of claim 9 wherein a minor amount of a corrosion inhibiting hydraulic fluid additive is present in the mixture.
 12. A hydraulic pressure transmitting fluid consisting essentially of at least one synthetic orthoester having the general formula of at least one synthetic orthoester having the general formula represented by A or B:
 13. The hydraulic pressure transmitting fluid of claim 12 the synthetic orthoester component comprises tris (methyl triglycol) orthopropionate. 